1. Field of the Invention
The present invention is directed to a pumping system for producing well fluids from petroleum producing formations penetrated by a well and specifically the present invention includes the use of dual parallel tubing strings having the lower portions connected by a cross-over flow connection, one of the tubing strings forming a flow path for flowing production fluids to the surface and the other for providing a conduit for inserting, operating and removing an insert type pump used to lift well fluids from the well and to move the well fluids up the well to the surface through the cross-over flow connection and a flow control valve in the production flow path.
2. Description of Related Art
Pumping well fluids from wells penetrating producing formations has been done for many years. This is particularly true where heavy viscous oil must be moved to the surface. Often heavy viscous oils such as produced from California formations which are relatively close to the earth's surface contain sand and are difficult to pump. Steam and diluents have often been used to lower the viscosity of heavy crudes to improve flow and pumping efficiency; however, sand is still a major problem.
Heretofore dual tubing strings for a pumping system for producing petroleum have been suggested. For example, pumping installations utilizing parallel dual tubing strings are disclosed in U.S. Pat. Nos. 4,056,335 to Walter S. Secrest; U.S. Pat. No. 3,802,802 to F. Conrad Greer; and U.S. Pat. No. 3,167,019 to J. W. Harris.
There is still need, however, for a pumping system having dual production and power tubing strings which permit ease of operation and in which all of the movable parts of the pumping and flow control apparatus may be both removed from the tubing strings and replaced in the tubing strings without the need for removing the tubing strings from the well.